V267 - V266 BASE / JOINED PLAYER POPUP CANCEL + CHARACTER FOLDER SAFETY

1. Direct-IP entry remains normal. CONNECTION_IP is not cancelled or hidden.
2. After a remote client has actually joined the multiplayer session, stale native
   CONNECTION_ERROR / CONNECTION_JOINING / CONNECTION_WAITING_FOR_SERVER panels
   are closed so they cannot cover the joined character in the world.
3. characters_<account> remains the permanent account character storage.
4. The plain characters path remains access denied.
5. A router-created characters junction is detached without touching its account target.
6. If a real non-empty characters directory appears, it is moved to an inaccessible
   _DRAKHYSYS_DENIED_SHARED_CHARACTERS* isolation folder instead of recursively deleted.
   This prevents CHR/BIO loss while still keeping shared characters inaccessible to BG2.
7. Empty real characters directories may still be removed.
8. No automatic character backup, copy, restore, or respawn system is added.
9. V266 owner-only Character Record icon/right-click behavior and native Export remain unchanged.
